1664124421 has 2 divisors, whose sum is σ = 1664124422. Its totient is φ = 1664124420.

The previous prime is 1664124419. The next prime is 1664124437. The reversal of 1664124421 is 1244214661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1437471396 + 226653025 = 37914^2 + 15055^2 .

It is a cyclic number.

It is not a de Polignac number, because 1664124421 - 2¹ = 1664124419 is a prime.

Together with 1664124419, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1664124401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 832062210 + 832062211.

It is an arithmetic number, because the mean of its divisors is an integer number (832062211).

Almost surely, 2^1664124421 is an apocalyptic number.

It is an amenable number.

1664124421 is a deficient number, since it is larger than the sum of its proper divisors (1).

1664124421 is an equidigital number, since it uses as much as digits as its factorization.

1664124421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9216, while the sum is 31.

The square root of 1664124421 is about 40793.6811405884. The cubic root of 1664124421 is about 1185.0279616207.

The spelling of 1664124421 in words is "one billion, six hundred sixty-four million, one hundred twenty-four thousand, four hundred twenty-one".